Golf: spin direction resulting from striking out of the toe

Question

If a golf club strikes the ball out of the centre of the club face with the club path on the target line through impact, and the face square to target, the ball will move towards the target with no side-spin.

If the same shot is played but the impact is towards the toe of the club, the club face will open slightly as a result, and side spin will be imparted.

The question is: for a right handed golfer is the spin clockwise (ball path bends right) or anti-clockwise (ball path bends left).

I ask this question because my golf coach and I disagree on the answer. He is a very experienced and highly qualified coach. I know nothing about golf but I have a degree in physics. I'm looking for an answer with a link to a respected reference which backs it up.

Answer 1

If a golf club strikes the ball out of the centre of the club face with the club path on the target line through impact, and the face square to target, the ball will move towards the target with no side-spin.

Correct.

If the same shot is played but the impact is towards the toe of the club, the club face will open slightly as a result, and side spin will be imparted.

Not entirely the case.

Although the tendency is for the face to open slightly as a result of impact toward the toe of the club, it is still possible to have the face square to target, meaning the ball will still move towards the target with no side-spin...albeit less backspin (and possibly less distance) because the ball didn't squarely make contact with the grooves, which is responsible for generating optimum spin.

Consider how forgiving drivers are with their massive sweet spots. A shot in which impact is off-center will still produce a similar shot to a shot in which impact is on-center, all things equal.

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AJ Bonar of The Truth About Golf₍₁₎ presents the following suggestion as physics-based. As you are more versed in physics than I am, I suggest examining this approach.

_{Disclaimer: I do not endorse Bonar's approach. In fact, I was bored from "The Truth About Golf" and didn't watch the entire instruction. However, I found his following suggestion to be helpful to my golf game.}

Bonar suggests that the direction the grooves are facing, not the direction of the clubface (open/closed), is the primary factor.

Ever open/close your stance, hit a shot in which the swing path is parallel to your stance, and end up hitting the shot toward the line of your stance? This is because: 1) Your stance lined up in that direction. 2) The grooves were parallel to the ground when you made impact with the ball. Thus, resulting in a straight shot to the direction in which your stance was opened/closed.

Consider your address position. If you are standing too far away from the ball and make solid impact with the ball, what is the ball doing? The ball is most likely drawing because the grooves were leaning toward you at impact. Now, if you are standing too close to the ball, the ball is most likely fading because the grooves were leaning away from you at impact.

The best illustration I can think of is of a golfer going "over-the-top." Notice on the downswing how upright the club had become from address as a result of going over-the-top. The result from here is a slice or push-slice as the grooves were leaning away from the golfer at impact.

for a right handed golfer is the spin clockwise (ball path bends right) or anti-clockwise (ball path bends left).

Based on my last few paragraphs, this depends on what direction your grooves are facing at impact. If your grooves are leaning toward you, the ball is spinning counter-clockwise (ball is drawing/hooking or bending left). If your grooves are leaning away from you, the ball is spinning clockwise (ball is fading/slicing or bending right). If your grooves are parallel to the ground at impact, there is no side-spin.

_{NOTE: My answer is based on the right-handed golfer.}

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I have played golf for 15+ years, came across this several years ago, and came away with a better understanding of how to draw/fade shots.

Answer 2

A toe strike will cause the face to open (face rotating clockwise) and the ball will spin counter-clockwise. This is called the "gear effect" and is named so because of how the face and the ball "mesh" together like gears.

This is mostly noticeable with woods and drivers because their center of gravity is farther behind the face of the club, as compared to irons. This is why wood faces are not flat, so as to counteract the spin of the ball.

You'll notice the toe of the club points more to the right (for a righty) than the center of the face, and the heel points more left. This is to encourage the ball to start out to the right (for a toe shot) to counteract the counter-clockwise spin on the ball, and hopefully the ball ends more in the center of the fairway.

I note that you question this answer because golfers slice the ball, and my answer is conditioned on the premise that the path of the clubhead is fairly neutral. A bad player who cuts across the ball can certainly spin the ball clockwise with a toe hit, but the ball would spin LESS clockwise than a center hit. Likewise, a player who has the clubface wide open at impact can also counteract this gear effect to a certain degree. After all, the face impact is only one variable in the impact of a golf ball.

Answer 3

The answer is: anti-clockwise (for a right-handed

This is contrary to what seems (to me anyway) to be intuitively obvious. The mechanism at work is the same as two adjacent rotating gears - they rotate in opposite directions. Indeed, this phenomenon is known as the 'gear effect'.

The club face rotates clockwise (opens) which imparts anti-clockwise spin to the ball.

The question should have been put better because this effect is only noticeable if the centre of mass of the club is well behind the face (like on a driver or wood). This is because the rotation of the club around the CoM causes the face to move right, pushing the back of the ball right, spinning it anti-clockwise.

Answer 4

If the face and path match up to the target at impact (zero path and zero face) and the ball is struck towards the toe of the club, the ball will start to the right (for right handed player) and curve back to the left. This is know as gear effect. Its more exaggerated in a driver due to the center of gravity of a driver being further back in the head than an iron. How far the ball starts right and curves depends how far towards the toe the ball is struck